From ddd553079578b0afbde70b340c924b6b15f6771e Mon Sep 17 00:00:00 2001
From: Chris <chris@raisingchris.com>
Date: Thu, 5 Nov 2026 07:03:47 -0500
Subject: [PATCH 1/2] Add failing test: %gui asyncio polls every millisecond
 (#1532)

---
 tests/test_eventloop.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tests/test_eventloop.py b/tests/test_eventloop.py
index a95d6338d..599361d8d 100644
--- a/tests/test_eventloop.py
+++ b/tests/test_eventloop.py
@@ -93,6 +93,26 @@ def do_thing():
     loop_asyncio(kernel)
 
 
+@windows_skip
+async def test_asyncio_gui_does_not_poll(kernel):
+    # The kernel already runs on asyncio, so `%gui asyncio` has nothing to poll (#1532).
+    calls = []
+    call_later = kernel.io_loop.call_later
+
+    def counting_call_later(delay, callback, *args, **kwargs):
+        calls.append(callback)
+        return call_later(delay, callback, *args, **kwargs)
+
+    kernel.io_loop.call_later = counting_call_later
+    try:
+        kernel.eventloop = loop_asyncio
+        await asyncio.sleep(0.1)
+    finally:
+        kernel.eventloop = None
+        del kernel.io_loop.call_later
+    assert len(calls) <= 1
+
+
 @windows_skip
 def test_enable_gui(kernel):
     enable_gui("tk", kernel)

From 51062bfedfe64e7a4bdbec436b926cd4b18404f8 Mon Sep 17 00:00:00 2001
From: Chris <chris@raisingchris.com>
Date: Thu, 5 Nov 2026 07:03:48 -0500
Subject: [PATCH 2/2] Don't poll for %gui asyncio; the kernel already runs on
 asyncio (fixes #1532)

---
 ipykernel/kernelbase.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/ipykernel/kernelbase.py b/ipykernel/kernelbase.py
index e6705cfc8..51e86c76f 100644
--- a/ipykernel/kernelbase.py
+++ b/ipykernel/kernelbase.py
@@ -543,6 +543,14 @@ def enter_eventloop(self):
             self.log.info("Exiting as there is no eventloop")
             return
 
+        from .eventloops import loop_asyncio
+
+        if eventloop is loop_asyncio:
+            # The kernel already runs on asyncio, so there is nothing to poll.
+            # Polling every millisecond would only burn CPU (#1532).
+            self.log.info("Kernel already runs on asyncio; no polling needed")
+            return
+
         async def advance_eventloop():
             # check if eventloop changed:
             if self.eventloop is not eventloop: